By Jack Mendel Copenhagen’s historic stock exchange was engulfed in flames today as its famous spire came crashing down. One of the oldest buildings in the Danish capital, the fire began on Tuesday in the copper roof of the 17th Century Old Stock Exchange, known as the Boersen, before spreading to the rest of the building. Footage on social media showed the fire engulfing much of the building, with the famous spire collapsing onto the road below. One of Copenhagen’s oldest buildings is on fire and its famous spire has collapsed. Parts of the roof have also collapsed, said firefighters’ spokesm…